Gearing for instrument dials



` Apri1z4. 1928. A f M. E.vANs|cKLE GEARING FOR INSTRUMENT DIALS Filed Feb. 2. 1924 I "im lf yr M" l A Troj/11? MELVIN E..

HENTS, T IBRANDESVLABOBATOBIES. ING., 0F

ZPORATION 0F JERSEY.

i PATENT oFFlcr..l

VANSIGKLE, OF NEWARK, NEW JEB8EY,' ASSIGNUB, BY mi ASSIGN- navman, Naw annali?, a. conenanmo ron INSTRUMENT mana `Application led. February 2, '1924. Serial Ho.`690,1168.

My invention relates broadly to electrical apparatus, and more particularly to the construction ofa device vfor adjusting various electrical'i-nstruments.-

provide a gearing for a dial secured upon the operating shaftof an electrical instrument for rotating the vshaft with precision of movement.

Another object of the invention is to provide a gearing for a dial for the rotation of an instrument 'shaft in which the dial carries a planetary gear which may be engaged with a 'fixed gear or .surface for ro- 15.tating the instrument shaft through extremely minute angles.

4,Still another objectA my invention is to provide a construction of dial comprising a disk arranged to be' secured upon the extremity of an instrument shaft v tively small adjusting gear mounted to ro.- tate upon an axis at right angles to the axis of the dial and located in a position-adjacent the periphery of the dial and arranged in such manner that the small ad-4 justing gear operates to roll upon a panel or cover for the instrument to rotate the instrument 'shaft through variable increments of distance. Y

My invention-linds particular application in radio lapparatus where ineness in tuning adjustment becomes essential Qin securing selectivity. In variable condensers employed in association with a coil antenna or inshunt with the secondary circuit of' a -receiving system, Small capacity changes cause considerable difference in tuning. In adjusting the .inductive relation of coils in tuning inductaces minute changes in angular 40 position cause great change inl-tuning adjustments. Itis or this purpose that I have developed a v'gearing for a dial which may be secured to the rotatable shaft of the instrument which projects through an instrument case or panel. The gearing engages with the surface of the instrument case or panel and enables me to secure rotation of the instrument shaft' through extremely small angles. 1 My invention will belmore clearly understood by reference ,tov the accompanying drawings, in which: Figure 1 is a plan view showin the `arrangement of the gearing for the dlal where One of the objects of my invention is toV with 'a relathe dial' is secured to the extremity of an instrument shaft which protrudes through a panel behind which the apparatus may be located; Fig. 2 is a side elevation showing the dial gearing and a fragmentary port1on of thepanel behind which the apparatus 1s positioned; Fig. 3 is a cross sectional view ot my dial gearing; and Fig. 4 is an enlarged detailed fragmentar section showing the planetary gear which l' mount within the dial.

,In the drawings, the panel has been represented by reference character 1. The instrumentshaft which projects through an aperture 1n the panel is shown by reference character 2. The dial is represented by reference character 3 and includes a disk shaped portion 4 and a knob portion 5 by which the r dial may be grasped andturned. The disk portion may be suitably calibrated as represented at' 6 to cooperate with an index on panel 1 to determine the relative rotation of the instrument shaft 2. In one position adjacent the periphery of the disk portion 4 I p rovlde an upstanding or enlarged projection 7 'integral with the disk portion 4. A

-slot .8 is provided in this enlarged portion 7 in a line at right angles to a radial line through the disk 4. Interposed between the parallel walls of the slot 8 I mount a relatively small rotatable member 9. The rotatable member 9 is centered upon a sleeve bearing 10 mounted to rotate upon screw member 11 as an axis. The screw member 11 engages an insert l2carried in the disk member4 and is screwed into the insert by revolving screw head 14 from the peripheral edge of the enlar ed portion? on disk 4.

In the operation o my gearing for dials, the dial is properly positioned on the instrument shaft 2 by means' of set screw 15 at such a distance from the panel 1 that the rotaryy member' 9 frictionally engages the surface of panel 1. In order to move the instrument shaft -through extremely small increments of distance the linger fmay be employed to revolve the rotary member 9 operating to rotate the instrument shaft -in proportion to the ratio ofthe diameter of the rotary tween the central ,axis of the dial and the member 9 andathe distance Abecenter line'/ of the rotary member 9. In

the dial is grasped and rotated to the desired angle. It will be appreciated that with m construction an extremely tine Vernier a invention other than are imposed by the' scope of the ap ended claim. t

Having thus escribed my invention, what I claim and desire to secure by Letters Pat-- ent ofthe United States is as follows:

A dial for revolving an instrument shaft c arranged to project through a stationary have described' my invention in panel com rising a rotatable member having a central nob thereon, a substantially fiat circular portion extending Y from said. knob,

a shaft member projecting through the pe ripheral edge of said circular portion in aY radial direction and screw threaded into said circular, portion, a roller journaled on said shaft member and projecting through said flat circular portion for frictionally engaging the surface of said stationary panel,

said at- .crculan portion being beveled around its peripheral edge on .opposite sides of' said shaft. member for receiving indicia thereon. A

` In testimony whereof aix my signature.

i A MEL'VINE vApNsIicKLE. 

